This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A197221 #12 Jun 08 2017 18:44:51 %S A197221 1,11,12,23,35,58,325,383,4155,12848,119787,132635,385057,9374003, %T A197221 1331493483,4003854452,5335347935,20009898257,85374940963, %U A197221 105384839220,717683976283,823068815503,4833028053798,10489124923099,25811277899996,36300402823095 %N A197221 Denominator of convergents to e + 1/e. %H A197221 Robert Israel, <a href="/A197221/b197221.txt">Table of n, a(n) for n = 1..1899</a> %p A197221 numtheory:-cfrac(exp(1)+exp(-1), 100, 'ccon'): %p A197221 map(denom, ccon[1..-2]); # _Robert Israel_, Jun 08 2017 %t A197221 Denominator[Convergents[E + 1/E, 40]] %Y A197221 Cf. A137204 (decimal), A197220 (numerators). %K A197221 nonn %O A197221 1,2 %A A197221 _T. D. Noe_, Oct 12 2011